In the first positional preview, USCfootball.com broke down the quarterback position, which remains a little bit of a question after losing John David Booty to graduation and the NFL Draft.

This week, we'll break down one of the strongest units in the country - the Trojan running backs and fullbacks.

Last year

Before the season began, national attention focused on the talented Trojan backfield, littered with former four and five-star prospects.

Before the season even began, the backfield lost Emanuel Moody, who transferred to Florida.

C.J. Gable started USC's first two games and appeared in a third before suffering a season-ending injury the required surgery.

With Gable out, senior Chauncey Washington started the next 10 games on his way to being the team's leading rusher. Washington ran for 992 yards and 10 touchdowns on 195 carries - all team-highs.

Joe McKnight got a start for USC in the Trojans' Rose Bowl win over Illinois, rushing for 125 yards and a touchdown on just 10 carries.

Stafon Johnson, the Trojans' second-leading rusher in 2007, also had a big game against the Illini, running for 104 yards on carries.

Fullback Stanley Havili started every game as a redshirt freshman and put together a very solid season. Havili rushed 21 times for 134 yards and two scores while catching 34 passes for 248 yards and five scores.

2008

With Gable back healthy from injury, the Trojan running backs shouldn't suffer much from the loss of Washington.

Gable said he's back 100 percent from a groin injury that slowed his progress in the spring, and he's intent on being on the field for plenty of reps.

""I want to be that (three)-down kind of back, where they can keep me in for pass blocking and everything," he said. "That's one of the most important things. A lot of running backs just run the ball, but you need someone who can do all of it."

Gable, though, will be battling Johnson for first-team reps.

Johnson backed up his breakout 2007 season with a very impressive showing in the spring.

Johnson said he's using the competition between teammates to help push his game to the next level.

"(I) just know that the game starts today," he said. "The day you slack off is the day that the other team is getting ahead of you as far as preparation is concerned.

"Knowing yourself, you have to push your teammates because you are only as good as your weakest link. If you are with all the running backs, you have to make sure everyone is pushed to a certain extent, same with the linemen and everyone else. Just make sure everybody is working hard as one unit to make one dominate team."

While Gable and Johnson are similar runners, the rest of the Trojan backfield offers unique skills the USC offense can use in its arsenal.

Perhaps the most exciting player returning on the offensive side of the ball, McKnight's been spending his spring working on becoming an even more explosive runner.

After missing some time during the spring after dropping a course, McKnight's focused on having a great summer to make up for lost time.

He's started by bulking up to 205 pounds.

"I'm trying to get some solid weight on me. I'm also trying to get even more explosive. I already feel more explosive," he said. "I feel faster. I'm just trying to keep my weight steady. I'd get to where I want, and I'd keep dropping it."

McKnight's a versatile weapon that can be used in the running, passing and return game, which should have him on the field plenty in his sophomore season.

Unlike the other backs, Allen Bradford has a specific plan for his upcoming season.

"I'm a power back," Bradford said. "I don't take offense to that. I know I've got the speed."

Bradford showed big-play ability in fall and spring practices, but he's yet to break a run in a game. He showed get plenty of short-yardage attempts.

"I'm back to where I was football-wise. I just have to keep putting in work, getting better."

Havili, a talented, versatile fullback, returns to the starting lineup. Havili will have a chance to be one of the best fullbacks in the country. He'll be backed up by Adam Goodman, who's looked good catching passes out of the backfield in seven-on-seven workouts.